1. Field of Invention
This invention relates generally to foam-plastic aromatic figures and other decorative objects, and more particularly to a technique for forming an in situ figure of this type within the cavity of a blister pack which initially functions as a mold therefor and then as a protective display package.
2. Status of Prior Art
Foam plastic material can be made in various densities and in varying degrees of resilience and hardness, so that the material can be soft and spongy, semi-flexible or hard and rigid. To produce a plastic foam material having a myriad of open cells, use may be made for this purpose of a blowing agent that generates gas through thermal decomposition in the polymer liquid or melt, or gas may be injected into the melt which expands during pressure relief. Gas may also be generated as a by-product of a chemical condensation reaction during cross-linking.
Various types of foam-forming polymer mixtures are disclosed in the Seefried U.S. Pat. No. 4,111,865, and in the Weisman U.S. Pat. No. 4,439,548. The invention is not limited to any one form of foam plastic material, for to create a foam plastic figure, use may be made of polyurethane, polyvinyl or any other known form of foam material which has dispersed therein a volatile liquid fragrance that is exuded when the figure is exposed to the atmosphere.
The concern of the present invention is with an article in the form of a decorative figure or other attractive object made of foam plastic material that has dispersed therein a volatile liquid fragrance, whereby the article is capable of exuding the fragrance continuously for a prolonged period.
A decorative sponge-like object of this type can be created with existing techniques by injecting the foam-forming mixture that incorporates the liquid fragrance into a shaped mold having the appropriate configuration. Because of the gas generated, the mixture expands in the mold to conform to the contours thereof, and it then cures in the mold to form the desired object. Finally, the object is removed from the mold and suitably packaged.
The problem encountered when seeking to produce shaped sponge-like objects of foam plastic material is that the cycle time for forming the sponge is considerably longer than with ordinary plastics which do not expand within the mold. Hence the cost per shot is substantially greater than it would be for a regular injection molding operation. Moreover, foam-forming materials used in the molding process are somewhat toxic prior to the sponge reaction and therefore have to be handled in a special environment. To further complicate matters, setting up machines to operate on foam requires many hours of transition time from the normal everyday injection molding process.
It is known to package toy figures and other articles of merchandise in a so-called blister pack. This pack is formed by a film or blister of clear plastic that is vacuum molded to conform generally to the configuration of the shaped article to be packaged. The margin of this blister is bonded to a backing sheet, thereby sealing the article within the blister.
The advantage of a blister pack over a conventional package is that it not only protects the article contained therein against contamination, but it also serves to display the article, so that potential purchasers are able to see the article being offered for sale. After purchase, the blister is detached from its backing sheet to release the article from the pack.